User interface for a portion of a display screen



FIG. 1 is a front view of a user interface for a portion of a display screen showing our new design;

FIG. 2 is a front view of a second embodiment thereof; and,

FIG. 3 is a front view of a third embodiment thereof.

The broken lines of the portion of a display screen, images, and text are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 